--- [EMAIL PROTECTED] wrote: > There have been a few posts recently where people > have had problems with > nulls. Anyone got comments on the below before I > submit it to techdocs? > > TIA > > - Richard Huxton > > A Brief Guide to NULLs > ====================== > > What is a null? > =============== > A null is *not* an empty string. > A null is *not* a value. > A null is *not* a "special" value. > A null is the absence of a value. > > > What do nulls mean? > =================== > Well, they *should* mean one of two things: > 1. There is no applicable value > 2. There is a value but it is unknown
Good job!, it sure helps people who don't much background on formal database theory. What about adding this to the section "What does nulls mean" --> 3) No value has yet been assigned to that particular attribute (field). I think it would also be nice if you can add a section on functions that deals with NULL such as nullif() and coalesce(). These functions help users interpret NULL values. best regards, ludwig __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
